Hello
Over the past few months, we have been noticing darkened areas of grout in the floor tile. The entire first floor of the house is tiled.
Some of these areas go away, some get white powdery blooms, and most recently... two areas have pinhole puddles of water coming up through the grout.
We have checked the leak dial and it doesn't show any leaks.
There is no underground plumbing, so it can't be a "slab leak".
Our neighbor is a plumber, and he had no suggestions, found no leaks.
There is no defined pattern or pathway to follow... just random grout lines.
There is a bathroom with sink/toilet and unused shower, that is furthest from the moist grout.
The majority of the affected areas, are around the kitchen table, just outside the kitchen sink area.
Our first thought was to check the kitchen sink, since it is closest, but I was told the moisture source can be coming from anywhere, settling in another area completely.
Any ideas??
Thank you!

Where do you live, and how old is the house, and how long have you lived in it?
First floor all tile sounds like south. Much of the South has been oversaturated. Maybe ground water coming up through the slab. Maybe a crack, if the entire slab isn't involved. Go around your foundation and peer at every inch of concrete to look for side cracks, if your kitchen table is near an outside wall.
Also, where is your sewer line. It has to go through the slab somewhere. Even if the water isn't smelly it could happen just when a washer drains.
Ask the town building inspector if he knows about others being affected by high water table.

Bailey, to add to joy's good advice, check you downspouts making sure the water is directed away from house. Good luck

So your home is built on a slab and the piping is under the slab, right?